Ankle Sprains and Instability

Ankle sprains and chronic instability

Most ankle sprains injure the ligaments on the outside of the ankle. The anterior talofibular ligament (ATFL) is most commonly affected, sometimes together with the calcaneofibular ligament (CFL). Most sprains improve with non-operative care, but some people develop recurrent giving-way episodes, discomfort or a loss of confidence on uneven ground.

What is injured?

The ATFL helps resist forward movement and inward rotation of the talus; the CFL contributes to stability of the ankle and subtalar region. An injury to the syndesmosis (‘high ankle sprain’) is a different ligament problem and may require a different assessment and treatment pathway.

Symptoms

An acute sprain causes outer ankle tenderness, swelling, bruising and difficulty walking. Later symptoms may include recurrent sprains, giving way, difficulty with running or uneven surfaces, and persistent swelling. Mechanical instability (ligament laxity) and functional instability (impaired balance or neuromuscular control) often coexist; the distinction matters because surgery treats mechanical laxity but cannot replace rehabilitation.

Assessment and imaging

Examination includes foot alignment, tenderness, stability tests, gait, proprioception and peroneal strength. X-rays may exclude fracture, assess arthritis or identify certain associated injuries. MRI is considered when persistent symptoms suggest cartilage injury, peroneal tendon problems, impingement or another diagnosis. Stress X-rays may be useful in selected cases. A torn ligament visible on MRI is not, by itself, an indication for surgery.

Non-surgical treatment

Treatment usually begins with protection and progressive functional rehabilitation: ankle movement, calf and peroneal strengthening, balance and proprioception, graded activity and sport-specific retraining. A lace-up brace or taping may reduce recurrence risk during higher-risk activities. Persistent instability should prompt assessment of rehabilitation quality and any associated conditions before deciding on surgery.

When is surgery considered?

Surgical stabilisation may be considered when recurrent mechanical giving way and demonstrable laxity continue despite an adequate rehabilitation programme (usually at least 3–6 months). It is not usually needed after one straightforward sprain. The decision also depends on activity needs, hyperlaxity, tissue quality, prior surgery, alignment and coexisting problems.

Anatomic ligament repair (modified Broström-type)

Where viable ligament tissue remains, the ATFL and sometimes CFL can be reattached or tightened to the fibula. In selected cases, the repair is reinforced with additional local tissue or a suture-based augmentation. These variations are not necessary for every patient. This is usually done through a small incision over the outside of the ankle and can sometimes be performed arthroscopically.

Graft reconstruction

When local tissue is insufficient, such as some revision or severe ligament-deficiency cases, a tendon graft can reconstruct the damaged ligaments. The operation should aim to restore stability without excessive restriction of normal movement.

Associated arthroscopy

Arthroscopy may be combined with stabilisation where there is symptomatic impingement, a loose body or an osteochondral lesion requiring treatment. Peroneal tendon pathology or alignment abnormalities may also need attention.

Recovery and risks

Initial immobilisation or boot protection is followed by staged physiotherapy. Running and change-of-direction sport usually resume only after healing, strength and control have recovered; timing varies by operation and any additional procedures. As a general guide, a boot is often worn for 2–6 weeks, running commonly resumes at around 3 months, and pivoting or contact sport at about 3–6 months. Most people can drive again at about 6–8 weeks. Risks include numbness from irritation of small skin nerves, stiffness, wound complications, persistent pain, recurrent laxity and blood clots. Contact the rooms promptly if you develop a fever, increasing wound redness or discharge, severe worsening pain or calf swelling after surgery; call 111 for chest pain or breathlessness.

Common questions

Do completely torn ankle ligaments always need surgery?
No. Many heal sufficiently with structured rehabilitation and bracing.

Why does my ankle still give way after physiotherapy?
Persistent ligament laxity, neuromuscular deficits or an associated joint/tendon problem may contribute.

Is an ankle ligament operation the same as syndesmosis surgery?
No. These stabilise different structures and have different indications.

Can recurrent sprains damage the cartilage?
Yes. Repeated injury and instability can be associated with cartilage damage and later arthritis.

Seeking specialist advice

Recurrent sprains, mechanical giving way or persistent pain despite rehabilitation may justify a foot-and-ankle assessment. Ankle sprains are injuries, so ACC may cover part of the cost; see the ACC questions on our Your appointment page.

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